Apparatus and method for forming 3d nanostructure electrode for electrochemical battery and capacitor

ABSTRACT

Embodiments described herein generally relate to an electrode structure for an electrochemical battery or capacitor, particularly, apparatus and methods of creating a reliable and cost efficient 3D electrode nano structure for an electrochemical battery or capacitor that has an improved lifetime, lower production costs, and improved process performance.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims benefit of U.S. provisional patent applicationSer. No. 61/117,535 (Attorney Docket No. 12922L), filed Nov. 24, 2008,which is herein incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

Embodiments of the present invention generally relate to apparatus andmethods of forming an electrochemical battery or capacitor.Particularly, embodiments of the present invention relates to apparatusand methods for forming electrochemical batteries or capacitors havingelectrodes with 3D nanostructure.

2. Description of the Related Art

Electrical energy can generally be stored in two fundamentally differentways: 1) indirectly in batteries as potential energy available aschemical energy that requires oxidation and reduction of active species,or 2) directly, using electrostatic charge formed on the plates of acapacitor. Typically, ordinary capacitors store a small amount of chargedue to their size and thus only store a small amount of electricalenergy. Energy storage in conventional capacitors is generallynon-Faradaic, meaning that no electron transfer takes place across anelectrode interface, and the storage of electric charge and energy iselectrostatic.

In an effort to form an effective electrical energy storage device thatcan store sufficient charge to be useful as independent power sources,or supplemental power source for a broad spectrum of portable electronicequipment and electric vehicles, devices known as electrochemicalcapacitors have been created. Electrochemical capacitors are energystorage devices which combine some aspects of the high energy storagepotential of batteries with the high energy transfer rate and highrecharging capabilities of capacitors.

The term electrochemical capacitor is sometimes described in the art asa super-capacitor, electrical double-layer capacitors, orultra-capacitor. Electrochemical capacitors can have hundreds of timesmore energy density than conventional capacitors and thousands of timeshigher power density than batteries. It should be noted that energystorage in electrochemical capacitors can be both Faradaic ornon-Faradaic.

In both the Faradaic electrochemical capacitors and non-Faradaicelectrochemical capacitors, capacitance is highly dependent on thecharacteristics of the electrode and electrode material. Ideally, theelectrode material should be electrically conducting and have a largesurface area. Typically, the electrode material will be formed fromporous structures to enable the formation of a large surface area thatcan be used either for the development of the electrical double layerfor static charge storage to provide non-Faradaic capacitance or for thereversible chemical redox reaction sites to provide Faradaiccapacitance.

An electrochemical battery is a device that converts chemical energyinto electrical energy. An electrochemical battery typically consists ofa group of electric cells that are connected to act as a source ofdirect current.

Generally, an electric cell consists of two dissimilar substances, apositive electrode and a negative electrode, and a third substance, anelectrolyte. The positive and negative electrodes conduct electricity.The electrolyte acts chemically on the electrodes. The two electrodesare connected by an external circuit, such as a piece of copper wire.

The electrolyte functions as an ionic conductor for the transfer of theelectrons between the electrodes. The voltage, or electromotive force,depends on the chemical properties of the substances used, but is notaffected by the size of the electrodes or the amount of electrolyte.

Electrochemical batteries are classed as either dry cell or wet cell. Ina dry cell, the electrolyte is absorbed in a porous medium, or isotherwise restrained from flowing. In a wet cell, the electrolyte is inliquid form and free to flow and move. Batteries also can be generallydivided into two main types—rechargeable and nonrechargeable, ordisposable.

Disposable batteries, also called primary cells, can be used until thechemical changes that induce the electrical current supply are complete,at which point the battery is discarded. Disposable batteries are mostcommonly used in smaller, portable devices that are only usedintermittently or at a large distance from an alternative power sourceor have a low current drain.

Rechargeable batteries, also called secondary cells, can be reused afterbeing drained. This is done by applying an external electrical current,which causes the chemical changes that occur in use to be reversed. Theexternal devices that supply the appropriate current are called chargersor rechargers.

Rechargeable batteries are sometimes known as storage batteries. Astorage battery is generally of the wet-cell type using a liquidelectrolyte and can be recharged many times. The storage batteryconsists of several cells connected in series. Each cell contains anumber of alternately positive and negative plates separated by theliquid electrolyte. The positive plates of the cell are connected toform the positive electrode and the negative plates form the negativeelectrode.

In the process of charging, each cell is made to operate in reverse ofits discharging operation. During charging, current is forced throughthe cell in the opposite direction as during discharging, causing thereverse of the chemical reaction that ordinarily takes place duringdischarge. Electrical energy is converted into stored chemical energyduring charging.

The storage battery's greatest use has been in the automobile where itwas used to start the internal-combustion engine. Improvements inbattery technology have resulted in vehicles in which the battery systemsupplies power to electric drive motors instead.

To make electrochemical batteries or capacitors more of a viableproduct, it is important to reduce the costs to produce theelectrochemical batteries or capacitors, and improve the efficiency ofthe formed electrochemical battery or capacitor device.

Therefore, there is a need for method and apparatus for formingelectrodes of electrochemical batteries or capacitors that have animproved lifetime, improved deposited film properties, and reducedproduction cost.

SUMMARY OF THE INVENTION

Embodiments described herein generally relate to an electrochemicalbattery and capacitor electrode structure, particularly, apparatus andmethods of creating a reliable and cost efficient electrochemicalbattery and capacitor electrode structure that has an improved lifetime,lower production costs, and improved process performance.

One embodiment of the present invention provides an apparatus forplating a metal on a large area substrate comprising a chamber bodydefining a processing volume, wherein the processing volume isconfigured to retain a plating bath therein, and the chamber body has anupper opening, a plurality of jet sprays configured to dispend a platingsolution to form the plating bath in the processing volume, wherein theplurality of jet sprays open to a side wall of the chamber body, adraining system configured to drain the plating bath from the processingvolume, an anode assembly disposed in the processing volume, wherein theanode assembly comprises an anode emerged in the plating bath in asubstantially vertical position, and a cathode assembly disposed in theprocessing volume, and the cathode assembly comprises a substratehandler configured position one or more large area substrates in asubstantially vertical position and substantially parallel to the anodethe processing volume, and a contacting mechanism configured to couplean electric bias to the one or more large area substrates.

Another embodiment of the present invention provides a substrateprocessing system comprising a pre-wetting chamber configured to clean aseed layer of a large area substrate, a first plating chamber configuredto form a columnar layer of a first metal on the seed layer of the largearea substrate, a second plating chamber configured to form a porouslayer over the columnar layer, a rinse dry chamber configured to cleanand dry the large are substrate, and a substrate transfer mechanismconfigured to transfer the large area substrate among the chambers,wherein each of the first and second plating chamber comprises a chamberbody defining a processing volume, wherein the processing volume isconfigured to retain a plating bath therein, and the chamber body has anupper opening, a draining system configured to drain the plating bathfrom the processing volume, an anode assembly disposed in the processingvolume, wherein the anode assembly comprises an anode emerged in theplating bath, and a cathode assembly disposed in the processing volume,and the cathode assembly comprises, a substrate handler configuredposition one or more large area substrates substantially parallel to theanode the processing volume, and a contacting mechanism configured tocouple an electric bias to the one or more large area substrates.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the presentinvention can be understood in detail, a more particular description ofthe invention, briefly summarized above, may be had by reference toembodiments, some of which are illustrated in the appended drawings. Itis to be noted, however, that the appended drawings illustrate onlytypical embodiments of this invention and are therefore not to beconsidered limiting of its scope, for the invention may admit to otherequally effective embodiments.

FIG. 1A is a simplified schematic view of an active region of anelectrochemical capacitor unit.

FIG. 1B is a simplified schematic view a lithium-ion battery cell.

FIG. 2 is a flow diagram of a method for forming an electrode inaccordance with embodiments described herein.

FIG. 3 is a schematic cross-sectional view showing formation an anodeaccording to embodiments of the present invention.

FIG. 4 is a flow diagram of a method for forming a porous electrode inaccordance with embodiments described herein.

FIG. 5A is a schematic sectional side view of a plating chamber inaccordance with one embodiment of the present invention.

FIG. 5B is a schematic sectional side view of the plating chamber ofFIG. 5A in a substrate transferring position.

FIG. 5C schematically illustrates a plating system using one or moreplating chambers of FIG. 5A.

FIG. 6A is a schematic sectional side view of a plating chamber inaccordance with one embodiment of the present invention.

FIG. 6B a schematic sectional side view of a plating chamber inaccordance with one embodiment of the present invention

FIG. 6C schematically illustrates a plating system using one or moreplating chambers of FIG. 6A.

FIG. 7A is a schematic perspective view of a plating chamber inaccordance with one embodiment of the present invention.

FIG. 7B is a schematic sectional side view of the plating chamber ofFIG. 7A in plating position.

FIG. 7C is a schematic view of a substrate holder in accordance with oneembodiment of the present invention.

FIGS. 8A-8B schematically illustrate a processing system in accordancewith one embodiment of the present invention.

To facilitate understanding, identical reference numerals have beenused, wherever possible, to designate identical elements that are commonto the figures. It is contemplated that elements and/or process steps ofone embodiment may be beneficially incorporated in other embodimentswithout additional recitation

DETAILED DESCRIPTION

Embodiments described herein generally relate to an electrode structure,particularly for an electrochemical battery or capacitor, apparatus andmethods of creating a reliable and cost efficient electrochemicalbattery or capacitor electrode structure that has an improved lifetime,lower production costs, and improved process performance. One embodimentprovides a substrate plating system comprising a first plating chamberconfigure to form a columnar structure on a seed layer of a substrate,and a second plating chamber configured to form a porous layer on thecolumnar structure. One embodiment provides a plating chamber configuredto plate one or more large area substrate. In one embodiment, theplating chamber comprises a feed roll, a bottom roll and a take up rollconfigured to position large area substrates formed in a continuousflexible base in a processing volume, and to transfer the large areasubstrates in and out the processing volume. In another embodiment, theplating chamber comprises a substrate holder movably disposed in aprocessing volume and configured to hold one or more large areasubstrate, and to transfer the one or more large area substrates in andout the processing volume.

In an effort to achieve high plating rates and achieve desirable platedfilm properties, it is often desirable to increase the concentration ofmetal ions near the cathode (e.g., seed layer surface) by reducing thediffusion boundary layer or by increasing the metal ion concentration inthe electrolyte bath. It should be noted that the diffusion boundarylayer is strongly related to the hydrodynamic boundary layer. If themetal ion concentration is too low and/or the diffusion boundary layeris too large at a desired plating rate the limiting current (i_(L)) willbe reached. The diffusion limited plating process created when thelimiting current is reached, prevents the increase in plating rate bythe application of more power (e.g., voltage) to the cathode (e.g.,metallized substrate surface). When the limiting current is reached alow density columnar film is produced due to the evolution of gas andresulting dendritic type film growth that occurs due to the masstransport limited process.

FIG. 1A illustrates a simplified schematic view of an active region 140of an electrochemical capacitor unit 100 that can be powered by use of apower source 160. An electrochemical capacitor unit 100 can be of anyshape, e.g., circular, square, rectangle, polygonal, and size. Theactive region 140 generally contains a membrane 110, porous electrodes120 formed according to embodiments described herein, charge collectorplates 150 and an electrolyte 130 that is in contact with the porouselectrodes 120, charge collector plates 150 and membrane 110. Theelectrically conductive charge collector plates 150 sandwich the porouselectrodes 120 and membrane 110.

The electrolyte 130 that is contained between the charge collectorplates 150 generally provides a charge reservoir for the electrochemicalcapacitor unit 100. The electrolyte 130 can be a solid or a fluidmaterial that has a desirable electrical resistance and properties toachieve desirable charge or discharge properties of the formed device.If the electrolyte is a fluid, the electrolyte enters the pores of theelectrode material and provides the ionic charge carriers for chargestorage. A fluid electrolyte requires that a membrane 110 benon-conducting to prevent shorting of the charge collected on either ofthe charge collector plates 150.

The membrane 110 is typically permeable to allow ion flow between theelectrodes and is fluid permeable. Examples of non-conducting permeableseparator material are porous hydrophilic polyethylene, polypropylene,fiberglass mats, and porous glass paper. The membrane 110 can be madefrom an ion exchange resin material, polymeric material, or a porousinorganic support. For example, three layers of polyolefin, three layersof polyolefin with ceramic particles, an ionic perfluoronated sulfonicacid polymer membrane, such as Nafion™, available from the E.I. DuPontde Nemeours & Co. Other suitable membrane materials include GoreSelect™, sulphonated fluorocarbon polymers, the polybenzimidazole (PBI)membrane (available from Celanese Chemicals, Dallas, Tex.), polyetherether ketone (PEEK) membranes and other materials.

The porous electrodes 120 generally contain a conductive material thathas a large surface area and has a desirable pore distribution to allowthe electrolyte 130 to permeate the structure. The porous electrodes 120generally require a large surface area to provide an area to form adouble-layer and/or an area to allow a reaction between the solid porouselectrode material and the electrolyte components, such aspseudo-capacitance type capacitors. The porous electrodes 120 can beformed from various metals, plastics, glass materials, graphites, orother suitable materials. In one embodiment, the porous electrode 120 ismade of any conductive material, such as a metal, plastic, graphite,polymers, carbon-containing polymer, composite, or other suitablematerials. More specifically, the porous electrode 120 may comprisecopper, aluminum, zinc, nickel, cobalt, palladium, platinum, tin,ruthenium, stainless steel, titanium, lithium, alloys thereof, andcombinations thereof.

Embodiments described herein, generally contain various apparatus andmethods for increasing the surface area of an electrode bythree-dimensional growth of electrode material. Advantageously, theincreased surface area of the porous three-dimensional electrodeprovides increased capacitance with improved cycling, rapid chargingusing the high conductivity three-dimensional nanomaterial, and largeenergy and power densities.

In one embodiment, three dimensional growth of electrode material isperformed using a high plating rate electroplating process performed atcurrent densities above the limiting current (i_(L)). In one embodiment,a columnar metal layer is formed at a first current density by adiffusion limited deposition process followed by the three dimensionalgrowth of electrode material at a second current density greater thanthe first current density. The resulting electrode structure has animproved lifetime, lower production cost, and improved processperformance.

FIG. 2B is a simplified schematic view of a lithium-ion battery cell158. Lithium-ion batteries are a type of electrochemical batteries. Aplurality of lithium-ion battery cells 150 can be assembled togetherwhen in use. The lithium-ion battery cell 150 comprises an anode 151,and a cathode 152, a separator 153, and an electrolyte 154 that is incontact with the anode 151, the cathode 152, the separator 153, and anelectrolyte 154 disposed between the anode 151 and the cathode 152.

Both the anode 151 and the cathode 152 comprise materials into which andfrom which lithium can migrate. The process of lithium moving into theanode 151 or cathode 152 is referred to as insertion or intercalation.The reverse process, in which lithium moves out of the anode 151 orcathode 152 is referred to as extraction or deintercalation. When thelithium-ion battery cell 150 is discharging, lithium is extracted fromthe anode 151 and inserted into the cathode 152. When the lithium-ionbattery cell 150 is charging, lithium is extracted from the cathode 152and inserted into the anode 151.

The anode 151 is configured to store lithium ions 155. The anode 151 maybe formed from carbon containing material or metallic material. Theanode 151 may comprise oxides, phosphates, fluorophosphates, orsilicates.

The cathode 152 may be made from a layered oxide, such as lithium cobaltoxide, a polyanion, such as lithium iron phosphate, a spinel, such aslithium manganese oxide, or TiS₂ (titanium disulfide). Exemplary oxidesmay be layered lithium cobalt oxide, or mixed metal oxide, such asLiNi_(x)Co_(1-2x)MnO₂, LiMn₂O₄. Li It is desirable that the anode 151has a large surface area. Exemplary phosphates may be iron olivine(LiFePO₄) and it is variants (such as LiFe1-_(x)MgPO₄), LiMoPO4,LiCoPO₄, Li₃V₂(PO₄)₃, LiVOPO₄, LiMP₂O₇, or LiFe_(1.5)P₂O₇. Exemplaryfluorophosphates may be LiVPO₄F, LiAlPO₄F, Li₅V(PO₄)₂F₂, Li₅Cr(PO₄)₂F₂,Li₂CoPO₄F, Li₂NiPO₄F, or Na₅V₂(PO₄)₂F₃. Exemplary silicates may beLi₂FeSiO₄, Li₂MnSiO₄, or Li₂VOSiO₄.

The separator 153 is configured to supply ion channels for in movementbetween the anode 151 and the cathode 152 while keeping the anode 151and the cathode 152 physically separated to avoid a short. The separator153 may be solid polymer, such as polyethyleneoxide (PEO).

The electrolyte 154 is generally a solution of lithium salts such asLiPF₆, LiBF₄, or LiClO₄, in an organic solvents.

When the lithium-ion battery cell 150 discharges, lithium ions 155 movesfrom the anode 151 to the cathode 152 providing a current to power aload 156 connected between the anode 151 and the cathode 152. When thelithium-ion battery cell 150 is depleted, a charger 157 may be connectedbetween the anode 151 and the cathode 152 providing a current to drivethe lithium ions 155 to the anode 151. Since the amount of energy storedin the lithium-ion battery cell 150 defends on the amount of lithium ion155 stored in the anode 151, it is desirable to have as large a surfacearea on the anode 151 as possible. Embodiments of the present inventiondescribed below provide methods and apparatus for producing electrodeswith increased surface area.

FIG. 2 is a flow diagram according to one embodiment described herein ofa process 200 for forming an electrode in accordance with embodimentsdescribed herein. FIG. 3 is a schematic cross-sectional view of anelectrode formed according to embodiments described herein. The process200 includes process steps 202-212, wherein an electrode is formed on asubstrate 220. The process 200 may be performed with systems inaccordance to embodiments of the present invention.

The first process step 202 includes providing the substrate 220. Thesubstrate 220 may comprise a material selected from the group comprisingcopper, aluminum, nickel, zinc, tin, flexible materials, stainlesssteel, and combinations thereof. Flexible substrates can be constructedfrom polymeric materials, such as a polyimide (e.g., KAPTON™ by DuPontCorporation), polyethyleneterephthalate (PET), polyacrylates,polycarbonate, silicone, epoxy resins, silicone-functionalized epoxyresins, polyester (e.g., MYLAR™ by E.I. du Pont de Nemours & Co.),APICAL AV manufactured by Kanegaftigi Chemical Industry Company, UPILEXmanufactured by UBE Industries, Ltd.; polyethersulfones (PES)manufactured by Sumitomo, a polyetherimide (e.g., ULTEM by GeneralElectric Company), and polyethylenenaphthalene (PEN). In some cases thesubstrate can be constructed from a metal foil, such as stainless steelthat has an insulating coating disposed thereon. Alternately, flexiblesubstrate can be constructed from a relatively thin glass that isreinforced with a polymeric coating.

The second process step 204 includes optionally depositing a barrierlayer over the substrate. The barrier layer 222 may be deposited toprevent or inhibit diffusion of subsequently deposited materials overthe barrier layer into the underlying substrate. Examples of barrierlayer materials include refractory metals and refractory metal nitridessuch as tantalum (Ta), tantalum nitride (TaN_(x)), titanium (Ti),titanium nitride (TiN_(x)), tungsten (W), tungsten nitride (WN_(x)), andcombinations thereof. Other examples of barrier layer materials includePVD titanium stuffed with nitrogen, doped silicon, aluminum, aluminumoxides, titanium silicon nitride, tungsten silicon nitride, andcombinations thereof. Exemplary barrier layers and barrier layerdeposition techniques are further described in U.S. Patent ApplicationPublication 2003/0143837 entitled “Method of Depositing A Catalytic SeedLayer,” filed on Jan. 28, 2002, which is incorporated herein byreference to the extent not inconsistent with the embodiments describedherein.

The barrier layer may be deposited by CVD, PVD, electroless depositiontechniques, evaporation, or molecular beam epitaxy. The barrier layermay also be a multi-layered film deposited individually or sequentiallyby the same or by a combination of techniques.

The third process step 206 includes optionally depositing a seed layer224 over the substrate 220. The seed layer 224 comprises a conductivemetal that aids in subsequent deposition of materials thereover. Theseed layer 224 preferably comprises a copper seed layer or alloysthereof. Other metals, particularly noble metals, may also be used forthe seed layer. The seed layer 224 may be deposited over the barrierlayer by techniques conventionally known in the art including physicalvapor deposition techniques, chemical vapor deposition techniques,evaporation, and electroless deposition techniques.

The fourth process step 208 includes forming a columnar metal layer 226over the seed layer 224. Formation of the columnar metal layer 226includes establishing process conditions under which evolution ofhydrogen results in the formation of a porous metal film. Formation ofthe columnar metal layer 226 generally takes place in a plating chamberusing a suitable plating solution. Suitable plating solutions that maybe used with the processes described herein to plate copper may includeat least one copper source compound, at least one acid basedelectrolyte, and optional additives.

The plating solution contains at least one copper source compoundcomplexed or chelated with at least one of a variety of ligands.Complexed copper includes a copper atom in the nucleus and surrounded byligands, functional groups, molecules or ions with a strong finite tothe copper, as opposed to free copper ions with very low finite, if any,to a ligand, such as water. Complexed copper sources are either chelatedbefore being added to the plating solution, such as copper citrate, orare formed in situ by combining a free copper ion source such as coppersulfate with a complexing agent, such as citric acid or sodium citrate.The copper atom may be in any oxidation state, such as 0, 1 or 2,before, during or after complexing with a ligand. Therefore, throughoutthe disclosure, the use of the word copper or elemental symbol Cuincludes the use of copper metal (Cu⁰), cupric (Cu⁺¹) or cuprous (Cu⁺²),unless otherwise distinguished or noted.

Examples of suitable copper source compounds include copper sulfate,copper phosphate, copper nitrate, copper citrate, copper tartrate,copper oxalate, copper EDTA, copper acetate, copper pyrophosphorate andcombinations thereof, preferably copper sulfate and/or copper citrate. Aparticular copper source compound may have ligated varieties. Forexample, copper citrate may include at least one cupric atom, cuprousatom or combinations thereof and at least one citrate ligand and includeCu(C₆H₇O₇), Cu₂(C₆H₄O₇), Cu₃(C₆H₅O₇) or Cu(C₆H₇O₇)₂. In another example,copper EDTA may include at least one cupric atom, cuprous atom orcombinations thereof and at least one EDTA ligand and includeCu(C₁₀H₁₅O₈N₂), Cu₂(C₁₀H₁₄O₈N₂), Cu₃(C₁₀H₁₃O₈N₂), Cu₄(C₁₀H₁₂O₈N₂),Cu(C₁₀H₁₄O₈N₂) or Cu₂(C₁₀H₁₂O₈N₂). The plating solution may include oneor more copper source compounds or complexed metal compounds at aconcentration in the range from about 0.02 M to about 0.8 M, preferablyin the range from about 0.1 M to about 0.5 M. For example, about 0.25 Mof copper sulfate may be used as a copper source compound.

Examples of suitable tin source may be soluble tin compound. A solubletin compound can be a stannic or stannous salt. The stannic or stannoussalt can be a sulfate, an alkane sulfonate, or an alkanol sulfonate. Forexample, the bath soluble tin compound can be one or more stannousalkane sulfonates of the formula:

(RSO₃)₂Sn

where R is an alkyl group that includes from one to twelve carbon atoms.The stannous alkane sulfonate can be stannous methane sulfonate with theformula:

The bath soluble tin compound can also be stannous sulfate of theformula: SnSO₄

Examples of the soluble tin compound can also include tin(II) salts oforganic sulfonic acid such as methanesulfonic acid, ethanesulfonic acid,2-propanolsulfonic acid, p-phenolsulfonic acid and like, tin(II)borofluoride, tin(II) sulfosuccinate, tin(II) sulfate, tin(II) oxide,tin(II) chloride and the like. These soluble tin(II) compounds may beused alone or in combination of two or more kinds.

Example of suitable cobalt source may include cobalt salt selected fromcobalt sulfate, cobalt nitrate, cobalt chloride, cobalt bromide, cobaltcarbonate, cobalt acetate, ethylene diamine tetraacetic acid cobalt,cobalt (II) acetyl acetonate, cobalt (III) acetyl acetonate, glycinecobalt (III), and cobalt pyrophosphate, or combinations thereof.

In one embodiment, the plating solution contains free copper ions inplace of copper source compounds and complexed copper ions.

The plating solution may contain at least one or more acid basedelectrolytes. Suitable acid based electrolyte systems include, forexample, sulfuric acid based electrolytes, phosphoric acid basedelectrolytes, perchloric acid based electrolytes, acetic acid basedelectrolytes, and combinations thereof. Suitable acid based electrolytesystems include an acid electrolyte, such as phosphoric acid andsulfuric acid, as well as acid electrolyte derivatives, includingammonium and potassium salts thereof. The acid based electrolyte systemmay also buffer the composition to maintain a desired pH level forprocessing a substrate.

Optionally, the plating solution may contain one or more chelating orcomplexing compounds and include compounds having one or more functionalgroups selected from the group of carboxylate groups, hydroxyl groups,alkoxyl, oxo acids groups, mixture of hydroxyl and carboxylate groupsand combinations thereof. Examples of suitable chelating compoundshaving one or more carboxylate groups include citric acid, tartaricacid, pyrophosphoric acid, succinic acid, oxalic acid, and combinationsthereof. Other suitable acids having one or more carboxylate groupsinclude acetic acid, adipic acid, butyric acid, capric acid, caproicacid, caprylic acid, glutaric acid, glycolic acid, formic acid, fumaricacid, lactic acid, lauric acid, malic acid, maleic acid, malonic acid,myristic acid, plamitic acid, phthalic acid, propionic acid, pyruvicacid, stearic acid, valeric acid, quinaldine acid, glycine, anthranilicacid, phenylalanine and combinations thereof. Further examples ofsuitable chelating compounds include compounds having one or more amineand amide functional groups, such as ethylenediamine,diethylenetriamine, diethylenetriamine derivatives, hexadiamine, aminoacids, ethylenediaminetetraacetic acid, methylformamide or combinationsthereof. The plating solution may include one or more chelating agentsat a concentration in the range from about 0.02 M to about 1.6 M,preferably in the range from about 0.2 M to about 1.0 M. For example,about 0.5 M of citric acid may be used as a chelating agent.

The one or more chelating compounds may also include salts of thechelating compounds described herein, such as lithium, sodium,potassium, cesium, calcium, magnesium, ammonium and combinationsthereof. The salts of chelating compounds may completely or onlypartially contain the aforementioned cations (e.g., sodium) as well asacidic protons, such as Na_(x)(C₆H_(8-x)O₇) or Na_(x)EDTA, whereasX=1-4. Such salt combines with a copper source to produce NaCu(C₆H₅O₇).Examples of suitable inorganic or organic acid salts include ammoniumand potassium salts or organic acids, such as ammonium oxalate, ammoniumcitrate, ammonium succinate, monobasic potassium citrate, dibasicpotassium citrate, tribasic potassium citrate, potassium tartrate,ammonium tartrate, potassium succinate, potassium oxalate, andcombinations thereof. The one or more chelating compounds may alsoinclude complexed salts, such as hydrates (e.g., sodium citratedihydrate).

Although the plating solutions are particularly useful for platingcopper, it is believed that the solutions also may be used fordepositing other conductive materials, such as platinum, tungsten,titanium, cobalt, gold, silver, ruthenium, tin, alloys thereof, andcombinations thereof. A copper precursor is substituted by a precursorcontaining the aforementioned metal and at least one ligand, such ascobalt citrate, cobalt sulfate or cobalt phosphate.

Optionally, wetting agents or suppressors, such as electricallyresistive additives that reduce the conductivity of the plating solutionmay be added to the solution in a range from about 10 ppm to about 2,000ppm, preferably in a range from about 50 ppm to about 1,000 ppm.Suppressors include polyacrylamide, polyacrylic acid polymers,polycarboxylate copolymers, polyethers or polyesters of ethylene oxideand/or propylene oxide (EO/PO), coconut diethanolamide, oleicdiethanolamide, ethanolamide derivatives or combinations thereof.

One or more pH-adjusting agents are optionally added to the platingsolution to achieve a pH less than 7, preferably between about 3 andabout 7, more preferably between about 4.5 and about 6.5. The amount ofpH adjusting agent can vary as the concentration of the other componentsis varied in different formulations. Different compounds may providedifferent pH levels for a given concentration, for example, thecomposition may include between about 0.1% and about 10% by volume of abase, such as potassium hydroxide, ammonium hydroxide or combinationsthereof, to provide the desired pH level. The one or more pH adjustingagents can be chosen from a class of acids including, carboxylic acids,such as acetic acid, citric acid, oxalic acid, phosphate-containingcomponents including phosphoric acid, ammonium phosphates, potassiumphosphates, inorganic acids, such as sulfuric acid, nitric acid,hydrochloric acid and combinations thereof.

The balance or remainder of the plating solution described herein is asolvent, such as a polar solvent. Water is a preferred solvent,preferably deionized water. Organic solvents, for example, alcohols orglycols, may also be used, but are generally included in an aqueoussolution.

Optionally, the plating solution may include one or more additivecompounds. Additive compounds include electrolyte additives including,but not limited to, suppressors, enhancers, levelers, brighteners andstabilizers to improve the effectiveness of the plating solution fordepositing metal, namely copper to the substrate surface. For example,certain additives may decrease the ionization rate of the metal atoms,thereby inhibiting the dissolution process, whereas other additives mayprovide a finished, shiny substrate surface. The additives may bepresent in the plating solution in concentrations up to about 15% byweight or volume, and may vary based upon the desired result afterplating.

In one embodiment, the plating solution includes at least one coppersource compound, at least one acid based electrolyte, and at least oneadditive, such as a chelating agent. In one embodiment, the at least onecopper source compound includes copper sulfate, the at least one acidbased electrolyte includes sulfuric acid, and the chelating compoundincludes citrate salt.

The columnar metal layer 226 is formed using a high plating ratedeposition process. The current densities of the deposition bias areselected such that the current densities are above the limiting current(i_(L)). When the limiting current is reached the columnar metal film isformed due to the evolution of hydrogen gas and resulting dendritic typefilm growth that occurs due to the mass transport limited process.During formation of the columnar metal layer, the deposition biasgenerally has a current density of about 10 A/cm² or less, preferablyabout 5 A/cm² or less, more preferably at about 3 A/cm² or less. In oneembodiment, the deposition bias has a current density in the range fromabout 0.5 A/cm² to about 3.0 A/cm², for example, about 2.0 A/cm².

The fifth process step 210 includes forming porous structure 228 on thecolumnar metal layer 226. The porous structure 228 may be formed on thecolumnar metal layer 226 by increasing the voltage and correspondingcurrent density from the deposition of the columnar metal layer. Thedeposition bias generally has a current density of about 10 A/cm² orless, preferably about 5 A/cm² or less, more preferably at about 3 A/cm²or less. In one embodiment, the deposition bias has a current density inthe range from about 0.5 A/cm² to about 3.0 A/cm², for example, about2.0 A/cm².

In one embodiment, the porous structure 228 may comprise one or more ofvarious forms of porosities. In one embodiment, the porous structure 228comprises macro porosity structure having pores of about 100 microns orless, wherein the non-porous portion of the macro porosity structurehaving pores of between about 2 nm to about 50 nm in diameter (mesoporosity). In another embodiment, the porous structure 228 comprisesmacro porosity structure having pores of about 30 microns. Additionally,surface of the porous structure 228 may comprise nano structures. Thecombination of micro porosity, meso porosity, and nano structureincreases surface area of the porous structure 408 tremendously.

In one embodiment, the porous structure 228 may be formed from a singlematerial, such as copper, zinc, nickel, cobalt, palladium, platinum,tin, ruthenium, and other suitable material. In another embodiment, theporous structure 228 may comprises alloy of copper, zinc, nickel,cobalt, palladium, platinum, tin, ruthenium, or other suitable material.

Optionally, a sixth processing step 212 can be performed to form apassivation layer 230 on the porous structure 228, as shown in FIG. 3F.The passivation layer 230 can be formed by an electrochemical platingprocess. The passiviation layer 230 provides high capacity and longcycle life for the electrode to be formed. In one embodiment, the porousstructure 228 comprises copper and tin alloy and the passivation layer230 comprises a tin film. In another embodiment, the porous structure228 comprises cobalt and tin alloy. In one embodiment, the passivationlayer 230 may be formed by emerging the substrate 220 in a new platingbath configured to plating the passivation layer 230 after a rinsingstep.

Embodiments of the present invention provide a processing system forcontinuously perform steps 208, 210, 212 of the process 200. FIG. 4 is aflow diagram of a method 250 for forming a porous electrode inaccordance with embodiments described herein. Each block in method 250is generally performed in a separated processing chamber. A substratebeing processed is generally streamlined from one chamber to the next tocomplete the process.

In block 252, a substrate deposited with a seed layer, by a PVD processor an evaporation process, is positioned in a pre-wetting chamber toremove oxides, carbon, or other contaminations before plating. Comparedto PVD process, evaporation process is generally at a lower cost.

In block 254, the pre-wetted substrate is emerged in a plating bath of afirst plating chamber to form a columnar metal layer.

In block 256, the substrate having the columnar metal layer formedthereon is removed from the first plating chamber and emerged in aplating bath of a second plating chamber to form a porous layer over thecolumnar metal layer.

In one embodiment, the columnar metal layer and the porous layer maycomprise the same metal, such as copper, and the plating baths in thefirst and second chambers may similar or compatible in chemistry. Inanother embodiment, the porous layer may comprise tin and copper alloy.In another embodiment, the porous layer may comprise cobalt and tinalloy. In another embodiment, the porous layer may comprise alloy ofcobalt, tin and copper.

In block 258, the substrate is rinsed in a rinsing chamber to remove anyresidual plating path on the substrate.

In block 260, the substrate is emerged in a plating bath in a thirdplating chamber to form a passivation thin film. In one embodiment, thepassivation thin film may comprise a thin film of tin.

In block 262, the substrate is rinsed and dried in a rinse-dry chamberfor subsequent processing.

FIGS. 5-8 describe chambers and systems configured to perform formationof an electrode for an electrochemical battery or capacitor using themethod 250.

FIG. 5A is a schematic sectional side view of a plating chamber 400 inaccordance with one embodiment of the present invention. The platingchamber 400 is in a plating position. FIG. 5B is a schematic sectionalside view of the plating chamber 400 in a substrate transferringposition.

The plating chamber 400 is configured to form a metal layer 306 over aseed layer 305, or a conductive layer, formed on a flexible base 301. Inone embodiment, the flexible base 301 is supplied to the plating chamber400 by portion by portion. Each portion may be considered a substrate.Each substrate is generally cut from the rest of the flexible base 301after processing.

In one embodiment, the plating chamber 400 is configured to deposit themetal layer 306 selectively over desired regions of the seed layer 305using a masking plate 410. The masking plate 410 has a plurality ofapertures 413 that preferentially allow the electrochemically depositedmaterial to form therein. In one embodiment, the masking plate 410 maydefine a pattern configured for a light-receiving side of the flexiblesolar cell.

The plating chamber 400 generally contains a head assembly 405, flexiblesubstrate assembly, an electrode 420, a power supply 450, a systemcontroller 251, and a plating cell assembly 430.

The plating cell assembly 430 generally contains a cell body 431defining a plating region 435 and an electrolyte collection region 436.In operation it is generally desirable to pump an electrolyte “A” fromthe electrolyte collection region 436 through a plenum 437 formedbetween the electrode 420 and the support features 434 past theapertures 413 formed in the masking plate 410 and then over a weir 432separating the plating region 435 and to the electrolyte collectionregion 436, by use of a pump 440.

In one embodiment, the electrode 420 may be supported on one or moresupport features 434 formed in the cell body 431. In one embodiment, theelectrode 420 contains a plurality of holes 421 that allow theelectrolyte “A” passing from the plenum 437 to the plating region 435 tohave a uniform flow distributed across masking plate 410 and contact atleast one surface on the flexible base 301. The fluid motion created bythe pump 440 allows the replenishment of the electrolyte components atthe exposed region 404 that is exposed at one ends of the apertures 413.

The electrode 420 may be formed from material that is consumable duringthe electroplating reaction, but is more preferably formed from anon-consumable material. A non-consumable electrode may be made of aconductive material that is not etched during the formation the metallayer 306, such as platinum or ruthenium coated titanium.

The head assembly 405 generally contains a thrust plate 414 and amasking plate 410 that is adapted to hold a portion of the flexible base301 in a position relative to the electrode 420 during theelectrochemical deposition process. In one aspect, a mechanical actuator415 is used to urge the thrust plate 414 and the flexible base 301against electrical contacts 412 formed on a top surface 418 of themasking plate 410 so that an electrical connection can be formed betweenthe seed layer 305 formed on the surface of the flexible base 301 andthe power supply 450 through the lead 451.

In one embodiment, as shown in FIG. 5A, the electrical contacts 412 areformed on a surface of the masking plate 410. In another embodiment, theelectrical contacts 412 may be formed from separate and discreteconductive contacts that are nested within a recess formed in themasking plate 410 when the flexible base 301 is being urged against themasking plate 410. The electrical contacts 412 may be formed from ametal, such as platinum, gold, or nickel, or another conductivematerial, such as graphite, copper Cu, phosphorous doped copper (CuP),and platinum coated titanium (Pt/Ti).

The flexible substrate assembly 460 comprises a feed roll 461 coupled toa feed actuator, and a take-up roll 462 coupled to a take-up actuator.The flexible substrate assembly 460 is configured to feed, positionportions of the flexible base 301 within the plating chamber 400 duringprocessing.

In one aspect, the feed roll 461 contains an amount of the flexible base301 on which a seed layer 305 has been formed. The take-up roll 462generally contains an amount of the flexible base 301 after the metallayer 306. The feed actuator and take-up actuator are used to positionand apply a desired tension to the flexible base 301 so that theelectrochemical processes can be performed on thereon. The feed actuatorand take-up actuator may be DC servo motor, stepper motor, mechanicalspring and brake, or other device that can be used to position and holdthe flexible substrate in a desired position with the plating chamber400.

FIG. 5B is a side cross-sectional view that illustrates the platingchamber 400 in transferring position to allow positioning a desiredportion of the flexible base 301 containing the seed layer 305 into adesired position relative to masking plate 410 and the electrode 420 sothat a metal layer 306 will be formed thereon. In on aspect, variousconvention encoders or other devices are used in conjunction with thefeed actuator and/or take-up actuator to control and position a desiredportion of the flexible base 301 containing the seed layer 305 withinthe head assembly 405.

FIG. 5C schematically illustrates a plating system 500 configured forplating an electrode of an electrochemical battery or capacitor using amethod similar to the method 250 described above.

The plating system 500 generally comprises a plurality of processingchambers arranged in a line, each configured to perform one processingstep to a substrate 511 formed on one portion of a continuous flexiblebase.

The plating system 500 comprises a pre-wetting chamber 501 configured topre-wet a substrate 511 formed on a portion of the flexible base. Thepre-wetting chamber 501 may be similar in structure to the platingchamber 400 of FIG. 5A without the electrodes 420, the masking plate410, and the power supply 450 required for plating process.

The plating system 500 further comprises a first plating chamber 502configured to perform a first plating process on the substrate 511 afterbeing pre-wetted. The first plating chamber 502 is generally disposednext to the cleaning pre-wetting station. In one embodiment, the firstplating process may be plating a columnar copper layer on a seed layerof formed on the substrate 511. The first plating chamber 502 may besimilar to the plating chamber 400 of FIG. 4A described above.

The plating system 500 further comprises a second plating chamber 503disposed next to the first plating chamber 502. The second platingchamber 503 is configured to perform a second plating process. In oneembodiment, the second plating process is forming a porous layer ofcopper or alloys on the columnar copper layer. The second platingchamber 503 may be similar to the plating chamber 400 of FIG. 4Adescribed above.

The plating system 500 further comprises a rinsing station 504 disposednext to the second plating chamber 503 and configured to rinse andremove any residual plating solution from the substrate 511. The rinsingstation 504 may be similar in structure to the plating chamber 400 ofFIG. 5A without the electrodes 420, the masking plate 410, and the powersupply 450 required for plating process.

The plating system 500 further comprises a third plating chamber 505disposed next to the rinsing station 504. The third plating chamber 505is configured to perform a third plating process. In one embodiment, thethird plating process is forming a thin film over the porous layer. Thethird plating chamber 505 may be similar to the plating chamber 400 ofFIG. 4A described above.

The plating system 500 further comprises a rinse-dry station 506disposed next to the third plating chamber 505 and configured to rinseand dry the substrate 511 after the plating processes and to get thesubstrate 511 ready for subsequent processing. The rinse-dry station 506may be similar in structure to the plating chamber 400 of FIG. 5Awithout the electrodes 420, the masking plate 410, and the power supply450 required for plating process. In one embodiment, the rinse-drystation 506 may comprise one or more vapor jets 506 a configured todirect a drying vapor toward the substrate 511 as the substrate 511exits the rinse-dry chamber 506.

The processing chambers 501-506 are generally arranged along a line sothat the substrates 511 can be streamlined through each chamber throughfeed rolls 507 ₁₋₆ and take up rolls 508 ₁₋₆ of each chamber. In oneembodiment, the feed rolls 507 ₁₋₆ and take up rolls 508 ₁₋₆ may beactivated simultaneously during substrate transferring step to move eachsubstrate 511 one chamber forward.

Substrates are positioned in a substantially horizontal position in thedescription of the plating system 500 above. However, other substrateorientations, such as vertical or tilted can be used in accordance withembodiments of the present invention.

FIG. 6A is a schematic sectional side view of a plating chamber 600 inaccordance with one embodiment of the present invention. The platingchamber 600 is configured to form a metal layer over a seed layer 602,or a conductive layer, formed on a flexible base 601. Similar to theplating chamber 400 of FIG. 5A, the flexible base 601 is supplied to theplating chamber 600 by portion by portion. Each portion may beconsidered a substrate. Each substrate is generally cut from the rest ofthe flexible base 601 after processing.

The plating chamber 600 generally comprises a chamber body 603 defininga processing volume 604. The processing volume 604 is in fluidcommunication with one or more inlet jet 605 configured to dispense aplating solution in the processing volume 604. The processing volume 604is also in fluid communication with a drain 606 configured to remove theplating solution from the processing volume 604.

The plating chamber 600 comprises a flexible substrate assembly 608configured to move the flexible base 601 and to position a particularportion the flexible base 601 in the processing volume 604 toprocessing. The flexible substrate assembly 608 comprises a feed roll609 disposed above the processing volume 604, a bottom roll 610 disposednear a bottom portion of the processing volume 604, a take-up roll 611disposed above the processing volume 604. Each of the feed roll 609, thebottom roll 610, and the take up roll 611 is configured to retain aportion of the flexible base 601. The flexible substrate assembly 608 isconfigured to feed, position portions of the flexible base 601 withinthe plating chamber 600 during processing.

In one embodiment, at least the feed roll 609 and the take up roll 611are coupled to actuators. The feed actuator and take-up actuator areused to position and apply a desired tension to the flexible base 601 sothat the electrochemical processes can be performed on thereon. The feedactuator and take-up actuator may be DC servo motor, stepper motor,mechanical spring and brake, or other device that can be used toposition and hold the flexible substrate in a desired position with theplating chamber 600.

The plating chamber 600 also comprises an anode assembly 607 disposed inthe processing volume 604. In one embodiment, the anode assembly 607 isdisposed in a substantially vertical orientation. In one embodiment, theanode assembly 607 may contains a plurality of holes that allow theplating bath passing from the inlet jets 605 to have a uniform flowdistributed across a plating surface of the flexible base 601.

The anode assembly 607 may be formed from material that is consumableduring the electroplating reaction, but is more preferably formed from anon-consumable material. A non-consumable electrode may be made of aconductive material that is not etched during the formation a metallayer over the flexible base 601, such as platinum or ruthenium coatedtitanium.

In one embodiment, the plating chamber 600 comprises a masking plate 613configured to selectively expose regions of the seed layer 602 duringprocessing. The masking plate 613 has a plurality of apertures 614 thatpreferentially allow the electrochemically deposited material to formtherein. In one embodiment, the masking plate 613 may define a patternconfigured for a light-receiving side of the flexible solar cell.

In one embodiment, the plating chamber 600 comprises a thrust plate 616disposed in the processing volume 604, substantially parallel to theanode assembly 607. The thrust plate 616 is configured to hold a portionof the flexible base 601 in a position relative to the anode assembly607 during the electrochemical deposition process. The thrust plate 616is positioned on a backside of the flexible base 601 and the anodeassembly 607 and masking plate 613 are positioned on a front side of theflexible base 601.

In one embodiment, the thrust plate 616 is horizontally movable. Duringtransferring stage, the thrust plate 616 is moved away from the flexiblebase 601 and neither the masking plate 613 nor the thrust plate 616 isin contact with the flexible base 601. Before processing, at least oneof the thrust plate 616 and the masking plate 613 is moved towards theother sandwiching the flexible base 601 in between. The thrust plate 616ensures that the flexible base 601 is substantially parallel to theanode assembly 607 and in a desired distance from the anode assembly607.

In one embodiment, a power source 617 ₁ is coupled between the anodeassembly 607 and the masking plate 613 to provide electric bias for aplating process. In one embodiment, a plurality of electrical contacts615 is formed on a surface of the masking plate 613. The power source617 ₁ is coupled to the plurality of electrical contacts 615 which thenprovides electrical bias to the seed layer 602 when the masking plate613 contacts the flexible base 601. The plurality of electrical contacts615 may be formed from separate and discrete conductive contacts thatare nested within a recess formed in the masking plate 613 when theflexible base 601 is being urged against the masking plate 613. Theelectrical contacts 615 may be formed from a metal, such as platinum,gold, or nickel, or another conductive material, such as graphite,copper Cu, phosphorous doped copper (CuP), and platinum coated titanium(Pt/Ti).

In another embodiment, a power source 617 ₂, instead of the power source617 ₁, is coupled between the anode assembly 607 and the seed layer 602directly. This is configuration is usually applicable when the seedlayer 602 is continuous within each portion (substrate) and isolatedfrom portion to portion.

In yet another embodiment, a power source 617 ₃, instead of the powersource 617 ₁, is coupled between the anode assembly 607 and the feedroll 609, which is in electrical contact with the flexible base 601.This is configuration is usually applicable when the flexible base 601is conductive.

FIG. 6B is a schematic sectional side view of a plating chamber 600 c inaccordance with one embodiment of the present invention. The platingchamber 600 c is similar to the plating chamber 600 of FIG. 6A exceptthat the plating chamber 600 c is configured to processing two portionsof the flexible base 601 simultaneously. This is configuration cannearly double the system throughput.

FIG. 6C schematically illustrates a plating system 700 using one or moreplating chambers of FIGS. 6A-6B. The plating system 700 configured forplating an electrode of an electrochemical battery or capacitor using amethod similar to the method 250 described above.

The plating system 700 generally comprises a plurality of processingchambers arranged in a line, each configured to perform one processingstep to a substrate formed on one portion of a continuous flexible base710.

The plating system 700 comprises a pre-wetting chamber 701 configured topre-wet a portion of the flexible base 710. The pre-wetting chamber 701may be similar in structure to the plating chambers 600, 600 c describedabove without the anode assembly 607, the masking plate 613, the thrustplate 616, and the power source 617 required for plating process.

The plating system 700 further comprises a first plating chamber 702configured to perform a first plating process the portion of theflexible base 710 after being pre-wetted. The first plating chamber 702is generally disposed next to the cleaning pre-wetting station. In oneembodiment, the first plating process may be plating a columnar copperlayer on a seed layer of formed on a seed layer formed on the portion ofthe flexible base 710. The first plating chamber 702 may be similar tothe plating chambers 600, 600 c described above.

The plating system 700 further comprises a second plating chamber 703disposed next to the first plating chamber 702. The second platingchamber 703 is configured to perform a second plating process. In oneembodiment, the second plating process is forming a porous layer ofcopper or alloys on the columnar copper layer. The second platingchamber 703 may be similar to the plating chambers 600, 600 c describedabove.

The plating system 700 further comprises a rinsing station 704 disposednext to the second plating chamber 703 and configured to rinse andremove any residual plating solution from the portion of flexible base710 processed by the second plating chamber 703. The rinsing station 704may be similar in structure to the plating chambers 600, 600 c describedabove without the anode assembly 607, the masking plate 613, the thrustplate 615, and the power source 617 required for plating process.

The plating system 700 further comprises a third plating chamber 705disposed next to the rinsing station 704. The third plating chamber 705is configured to perform a third plating process. In one embodiment, thethird plating process is forming a thin film over the porous layer. Thethird plating chamber 705 may be similar to the plating chambers 600,600 c described above.

The plating system 700 further comprises a rinse-dry station 706disposed next to the third plating chamber 705 and configured to rinseand dry the portion of flexible base 710 after the plating processes.The rinse-dry station 706 may be similar in structure to the platingchambers 600, 600 c described above without the anode assembly 607, themasking plate 613, the thrust plate 615, and the power source 617required for plating process. In one embodiment, the rinse-dry station706 may comprise one or more vapor jets 706 a configured to direct adrying vapor toward the flexible base 710 as the flexible base 710 exitsthe rinse-dry station 706.

The processing chambers 701-706 are generally arranged along a line sothat portions of the flexible base 710 can be streamlined through eachchamber through feed rolls 707 ₁₋₆ and take up rolls 708 ₁₋₆ of eachchamber. In one embodiment, the feed rolls 707 ₁₋₆ and take up rolls 708₁₋₆ may be activated simultaneously during substrate transferring stepto move each portion of the flexible base 710 one chamber forward.

FIG. 7A is a schematic perspective view of a plating chamber 800 inaccordance with one embodiment of the present invention. FIG. 7B is aschematic sectional side view of the plating chamber 800 of FIG. 7A inplating position.

The plating chamber 800 generally comprises a chamber body 801 defininga processing volume 802 configured retaining a plating bath forprocessing one or more substrates in a substantially vertical position.The processing volume 802 has a top opening 802 a configured to allowpassage of substrates being processed. The plating chamber comprises aplurality of inlet jets 803 disposed on a sidewall of the chamber body801. In one embodiment, the plurality of inlet jets 803 may bedistributed across the sidewall. The plurality of inlet jets 803 mayalso be used to spray wetting solution or cleaning solution towards asubstrate being processed. The plurality of inlet jets 803 are connectedto a plating solution source 804.

In one embodiment, the plating chamber 800 further comprises a drain 812configured to remove processing solution from the processing volume 802.In another embodiment, as shown in FIG. 7B, the plating chamber 800 maycomprise a catch pen 825 configured to retain plating solutionoverflowing from the top opening 802 a of the processing volume 802. Inone embodiment, the plating solution retained in the catch pen 825 maybe filtered and flown back to the plating solution source 804 for reuse.

The plating chamber 800 comprises an anode assembly 805 disposed in theprocessing volume 802 in a substantially vertical orientation. In oneembodiment, the anode assembly 805 may be removable from the processingvolume 802 for maintenance or replacement. In one embodiment, the anodeassembly 805 may contains a plurality of holes that allow the platingbath passing from the inlet jets 803 to have a uniform flow distributedacross the processing volume 802.

The anode assembly 805 may be formed from material that is consumableduring the electroplating reaction, but is more preferably formed from anon-consumable material. A non-consumable electrode may be made of aconductive material that is not etched during plating, such as platinumor ruthenium coated titanium. The advantages of non consumable anodesinclude low cost and maintenance for being non-consumable, inert tochemical, good for alloy combination, good for pulse condition,

The plating chamber 800 further comprises a cathode assembly 806configured to transfer one or more substrates 808 and position the oneor more substrates 808 in a plating position as shown in FIG. 7B. Asillustrated in FIG. 7A, the cathode assembly 806 can be lowered into theprocessing volume 802 via the top opening 802 a.

Flexible substrates are commonly used in producing some devices, such assolar battery cells. In one embodiment, the cathode assembly 806 isconfigured to support one or more flexible substrates for plating. Inone embodiment, the cathode assembly 806 may comprise a back plate 810configured to provide structural support to the substrate 808.

As discussed above, a plating process is generally performed to form ametal layer over a seed layer 809 formed on the substrate 808. Thecathode assembly 806 is configured to support the substrate 808 so thatthe seed layer 809 is facing the anode assembly 805.

In one embodiment, the cathode assembly 806 comprises a masking plate807 configured to selectively expose regions of the seed layer 809during processing. The masking plate 807 has a plurality of apertures807 a that preferentially allow the electrochemically deposited materialto form therein. In one embodiment, the masking plate 807 may define apattern configured for a light-receiving side of the flexible solarcell.

In one embodiment, the anode assembly 805 and the cathode assembly 806may be moved relative to each other to achieve a desired spacing betweenthe substrate 808 and the anode assembly 805 for plating.

A power source 811 is coupled between the anode assembly 805 and thesubstrate 808 to provide a bias for electroplating. In one embodiment, aplurality of electrical contacts 807 b is formed on a surface of themasking plate 807. In one embodiment, the power source 811 may beconnected to the substrate 808 via the electrical contacts 807 b of themasking plate 807. The electrical contacts 807 b may be formed from ametal, such as platinum, gold, or nickel, or another conductivematerial, such as graphite, copper Cu, phosphorous doped copper (CuP),and platinum coated titanium (Pt/Ti).

The cathode assembly 806 may be configured to support a single substrateor multiple substrates. FIG. 7C is a schematic view of the cathodeassembly 806 in accordance with one embodiment of the present invention.The cathode assembly 806 shown in FIG. 7C is configured to support 4substrates 808. The cathode assembly 806 comprises a supporting frame815 on which substrates 808 may be mounted.

FIGS. 8A-8B schematically illustrate a plating system 900 in accordancewith one embodiment of the present invention. The plating system 900comprises a plurality of processing chambers similar in structure to theplating chamber 800 of FIG. 7A. The plating system 900 configured forplating an electrode of an electrochemical battery or capacitor using amethod similar to the method 250 described above.

The plating system 900 generally comprises a plurality of processingchambers 901, 902, 903, 904, 905, 906 arranged in a line, eachconfigured to perform one processing step to substrates secured onsubstrate holders 907 ₁-907 ₆. The substrate holders 907 ₁-907 ₆ may betransferred by a substrate transferring mechanism 910 among theprocessing chambers 901-906.

In one embodiment, the substrate holders 907 ₁-907 ₆ are similar to thecathode assembly 806 of the plating chamber 800 described above.

In one embodiment, the processing chamber 901 may be a pre-wettingchamber configured to pre-wet a substrate disposed therein.

The processing chamber 902 may be a plating chamber configured toperform a first plating process the portion of the substrate after beingpre-wetted in the processing chamber 901. In one embodiment, the firstplating process may be configured to form a columnar metal layer over aseed layer of the substrate.

The processing chamber 903 may be a plating chamber configured toperform a second plating process the portion of the substrate after theplating process in the processing chamber 902. The second platingprocess may be configured to form a porous layer over the columnar metallayer.

The processing chamber 904 may be a rinsing chamber configured to rinseand remove any residual plating solution from the substrate after thesecond plating process in the processing chamber 903.

The processing chamber 905 may be a plating chamber configured toperform a third plating process. In one embodiment, the third platingprocess is configured to form a thin film over the porous layer.

The processing chamber 906 may be a rinse-dry station configured torinse and dry the substrate after the third plating process.

FIGS. 8A-8B illustrate a substrate transferring sequence duringprocessing. As shown in FIG. 8A, the substrate holder 907 ₆ may betransferred out of the processing chamber 906 having vapor jets 907 aafter drying, while the substrate transferring mechanism 910 is inposition to pick up substrate holders 907 ₁-907 ₅ in the processingchambers 901-905 simultaneously after processes are complete in eachchamber.

In FIG. 8B, the substrate transferring mechanism 910 picks up thesubstrate holders 907 ₁-907 ₅ from the processing chambers 901-905 andmoves the substrate holders 907 ₁-907 ₅ down the line to the nextchambers. The processing chamber 901 is ready for new substrates beingsecured in a new substrate holder 907 ₇.

The substrate transferring mechanism 910 drops the substrate holders 907₁-907 ₅ to the processing chambers 902-906 respectively. The processingchamber 901 processing the substrates secured in the substrate holder907 ₇.

The substrate transferring mechanism 910 moves backward to pick up thesubstrate holders 907 ₇, and 907 ₁-907 ₄ to the processing chambers901-905 respectively. The substrates in the substrate holder 907 ₅ areready to exit the plating system 900. These moving steps are repeatedfor a streamline process.

While the foregoing is directed to embodiments of the present invention,other and further embodiments of the invention may be devised withoutdeparting from the basic scope thereof, and the scope thereof isdetermined by the claims that follow.

1. An apparatus for plating a metal on a large area substrate,comprising: a chamber body defining a processing volume, wherein theprocessing volume is configured to retain a plating bath therein, andthe chamber body has an upper opening; a plurality of jet spraysconfigured to dispend a plating solution to form the plating bath in theprocessing volume, wherein the plurality of jet sprays open to a sidewall of the chamber body; a draining system configured to drain theplating bath from the processing volume; an anode assembly disposed inthe processing volume, wherein the anode assembly comprises an anodeemerged in the plating bath in a substantially vertical position; and acathode assembly disposed in the processing volume, and the cathodeassembly comprises: a substrate handler configured to position one ormore large area substrates substantially parallel to the anode in theprocessing volume; and a contacting mechanism configured to couple anelectric bias to the one or more large area substrates.
 2. The apparatusof claim 1, wherein the cathode assembly is configured to be loweredinto the processing volume to emerge the one or more large areasubstrates in the plating bath and lifted out the processing volume toretrieve the one or more large area substrates from the plating bath. 3.The apparatus of claim 2, wherein the contacting mechanism comprises amasking plate positioned against a plating surface of the one or morelarge area substrates, wherein the masking plate is configured to exposeportions of the one or more large areas substrates to be plated.
 4. Theapparatus of claim 3, wherein the masking plate comprises: a dielectricplate body having a plurality of through holes configured to defineareas to be plated; and a plurality of electrical contacts embedded inthe dielectric plate body, wherein the plurality of electrical contactsare in electrical connection with a power source, and the plurality ofelectrical contacts are configured to be in contact with the surface ofthe one or more large area substrates and not exposed to the platingbath.
 5. The apparatus of claim 4, wherein the substrate holder furthercomprises: a thrust plate configured to press the one or more large areasubstrates against the masking plate, wherein the masking plate and thethrust plate are positioned on opposite sides of the one or more largearea substrates.
 6. The apparatus of claim 1, wherein the cathodeassembly further comprises: a feed roll disposed out side the processingvolume and configured to retain a portion of a flexible base, whereinthe one or more large area substrates are formed on the flexible base; abottom roll disposed near a bottom portion of the processing volume andconfigured to retain a portion of the flexible base; and a take up rolldisposed out side the processing volume and configured to retain aportion of the flexible base, wherein the feed roll, bottom roll andtake up roll are configured to transfer the one or more large areasubstrates in and out the processing volume, and hold the one or morelarge area substrates in the processing volume by handling the flexiblebase.
 7. The apparatus of claim 6, further comprising: a thrust platemovably disposed in the processing volume, wherein the thrust plate isconfigured to push against a portion of the flexible base.
 8. Theapparatus of claim 7, further comprising: a masking plate positionedagainst a plating surface of the one or more large area substrates,wherein the masking plate is configured to expose portions of the one ormore large areas substrates to be plated.
 9. The apparatus of claim 8,wherein the masking plate comprises: a dielectric plate body having aplurality of through holes configured to define areas to be plated; anda plurality of electrical contacts embedded in the dielectric platebody, wherein the plurality of electrical contacts are in electricalconnection with a power source, and the plurality of electrical contactsare configured to be in contact with the surface of the one or morelarge area substrates and not exposed to the plating bath.
 10. Theapparatus of claim 6, further comprising: a power source connectedbetween the anode and a conductive layer formed on the surface of one ormore large area substrates, wherein the power source is connected to theconductive layer directly or via the feed roll.
 11. A substrateprocessing system, comprising: a pre-wetting chamber configured to cleana seed layer of a large area substrate; a first plating chamberconfigured to form a columnar layer of a first metal on the seed layerof the large area substrate; a second plating chamber configured to forma porous layer over the columnar layer; a rinse dry chamber configuredto clean and dry the large area substrate; and a substrate transfermechanism configured to transfer the large area substrate among thechambers, wherein each of the first and second plating chambercomprises: a chamber body defining a processing volume, wherein theprocessing volume is configured to retain a plating bath therein, andthe chamber body has an upper opening; a draining system configured todrain the plating bath from the processing volume; an anode assemblydisposed in the processing volume, wherein the anode assembly comprisesan anode emerged in the plating bath; and a cathode assembly disposed inthe processing volume, and the cathode assembly comprises: a substratehandler configured position one or more large area substratessubstantially parallel to the anode in the processing volume; and acontacting mechanism configured to couple an electric bias to the one ormore large area substrates.
 12. The substrate processing system of claim11, wherein the large area substrates are formed on a continuousflexible base, and each chamber comprises: a feed roll disposed out sidethe processing volume and configured to retain a portion of the flexiblebase; a bottom roll disposed near a bottom portion of the processingvolume and configured to retain a portion of the flexible base; and atake up roll disposed out side the processing volume and configured toretain a portion of the flexible base, wherein the substrate transfermechanism is configured to activate the feed rolls and the take up rollsto move the flexible base to transfer the one or more large areasubstrates in and out each chambers, and hold the one or more large areasubstrates in the processing volume of each chamber.
 13. The substrateprocessing system of claim 12, wherein the large area substrates arepositioned substantially vertical in each chamber during processing, andeach plating chamber further comprises a thrust plate movably disposedin the processing volume, wherein the thrust plate is configured to pushagainst a portion of the flexible base so that the one or more largearea substrates are proximate to and substantially parallel to theanode.
 14. The substrate processing system of claim 13, wherein eachplating chamber further comprises: a masking plate positioned against aplating surface of the one or more large area substrates, wherein themasking plate is configured to expose portions of the one or more largeareas substrates to be plated.
 15. The substrate processing system ofclaim 11, wherein the substrate handler comprises a substrate frameconfigured to hold the one or more large area substrates in the platingbath, and the substrate handler is configured to be transferred amongthe chambers.
 16. The substrate processing system of claim 15, whereinthe substrate transfer mechanism is configured to simultaneously liftthe substrate frame from each chamber, transfer the substrate framesover the chambers, and lower each substrate frame to a different chamberso that the one or more substrates are positioned for a subsequentprocessing step.
 17. The substrate processing system of claim 15,wherein the contacting mechanism of each plating chamber comprises amasking plate positioned against a plating surface of the one or morelarge area substrates, wherein the masking plate is configured to exposeportions of the one or more large areas substrates to be plated.
 18. Thesubstrate processing system of claim 12, wherein the second platingchamber is configured to form the porous layer of the first metal, andthe porous layer comprises at least one of macro porosity,micro-porousity, and meso-porousity.
 19. The substrate processing systemof claim 18, further comprising: a rinsing chamber configured to rinsethe large area substrate after formation of the porous layer in thesecond plating chamber; and a third plating chamber configured to platea layer of a second metal over the porous layer, wherein the first metalis different from the second metal.
 20. The substrate processing systemof claim 19, wherein the first metal is copper and the second metal istin.